Improve apps v2 upgrade UX

remoting/webapp/crd/js/host_list.js

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * @fileoverview
  * Class representing the host-list portion of the home screen UI.
  */
 
 'use strict';
@@ skipping 271 matching lines @@
   var canChangeLocalHostState =
       (state != remoting.HostController.State.NOT_IMPLEMENTED) &&
       (state != remoting.HostController.State.UNKNOWN) &&
       (state != remoting.HostController.State.NOT_INSTALLED ||
        remoting.isMe2MeInstallable()) &&
       (enabled || this.lastError_ == '');
 
   remoting.updateModalUi(enabled ? 'enabled' : 'disabled', 'data-daemon-state');
   var element = document.getElementById('daemon-control');
   element.hidden = !canChangeLocalHostState;
-  element = document.getElementById('host-list-empty-hosting-supported');
-  element.hidden = !canChangeLocalHostState;
-  element = document.getElementById('host-list-empty-hosting-unsupported');
-  element.hidden = canChangeLocalHostState;
+
+  if (noHostsRegistered) {
+    this.showHostListEmptyMessage_(canChangeLocalHostState);
+  }
 };
 
 /**
+ * Displays a message to the user when the host list is empty.
+ *
+ * @param {boolean} hostingSupported
+ * @return {void}
+ * @private
+ */
+remoting.HostList.prototype.showHostListEmptyMessage_ = function(
+    hostingSupported) {
+  var that = this;
+  remoting.AppsV2Migration.hasHostsInV1App().then(
+    /**
+     * @param {{ email: string, fullName: string}} previousIdentity

[Jamie, 2015/01/20 22:32:01]

Nit: No space before "email". Or it might be cleaner to use
remoting.MigrationSettings.

[kelvinp, 2015/01/21 21:16:21]

Done.

+     * @this {remoting.HostList}
+     */
+    function(previousIdentity) {
+      that.noHosts_.innerHTML = remoting.AppsV2Migration.buildMigrationTips(
+          previousIdentity.email, previousIdentity.fullName);
+    },
+    function() {
+      var buttonLabel = l10n.getTranslationOrError(
+          /*i18n-content*/'HOME_DAEMON_START_BUTTON');
+      if (hostingSupported) {
+        that.noHosts_.innerText = l10n.getTranslationOrError(
+            /*i18n-content*/'HOST_LIST_EMPTY_HOSTING_SUPPORTED',
+            [buttonLabel]);
+      } else {
+        that.noHosts_.innerText = l10n.getTranslationOrError(
+            /*i18n-content*/'HOST_LIST_EMPTY_HOSTING_UNSUPPORTED',
+            [buttonLabel]);
+      }
+    }
+  );
+};
+
+/**
  * Remove a host from the list, and deregister it.
  * @param {remoting.HostTableEntry} hostTableEntry The host to be removed.
  * @return {void} Nothing.
  * @private
  */
 remoting.HostList.prototype.deleteHost_ = function(hostTableEntry) {
   this.table_.removeChild(hostTableEntry.tableRow);
   var index = this.hostTableEntries_.indexOf(hostTableEntry);
   if (index != -1) {
     this.hostTableEntries_.splice(index, 1);
@@ skipping 146 matching lines @@
   }
 };
 
 /**
  * Save the host list to local storage.
  */
 remoting.HostList.prototype.save_ = function() {
   var items = {};
   items[remoting.HostList.HOSTS_KEY] = JSON.stringify(this.hosts_);
   chrome.storage.local.set(items);
+  remoting.AppsV2Migration.savePreferences(this.hosts_.length !== 0);
 };
 
 /**
  * Key name under which Me2Me hosts are cached.
  */
 remoting.HostList.HOSTS_KEY = 'me2me-cached-hosts';
 
 /** @type {remoting.HostList} */
 remoting.hostList = null;